Move code to handle loop wakeup and signals into its own module

2019-07-05 12:19:37 +05:30
parent 556992a117
commit 5dc4e79c8d
4 changed files with 182 additions and 109 deletions
--- a/kitty/loop-utils.c
+++ b/kitty/loop-utils.c
@@ -0,0 +1,94 @@
+/*
+ * loop-utils.c
+ * Copyright (C) 2019 Kovid Goyal <kovid at kovidgoyal.net>
+ *
+ * Distributed under terms of the GPL3 license.
+ */
+
+#include "loop-utils.h"
+#include <signal.h>
+
+bool
+init_loop_data(LoopData *ld) {
+    if (!self_pipe(ld->wakeup_fds, true)) return false;
+    ld->wakeup_read_fd = ld->wakeup_fds[0];
+    ld->signal_fds[0] = -1; ld->signal_fds[1] = -1; ld->signal_read_fd = -1;
+    return true;
+}
+
+static int signal_write_fd = -1;
+
+static void
+handle_signal(int sig_num) {
+    int save_err = errno;
+    unsigned char byte = (unsigned char)sig_num;
+    while(signal_write_fd != -1) {
+        ssize_t ret = write(signal_write_fd, &byte, 1);
+        if (ret < 0 && errno == EINTR) continue;
+        break;
+    }
+    errno = save_err;
+}
+
+
+void
+free_loop_data(LoopData *ld) {
+#define CLOSE(which, idx) if (ld->which[idx] > -1) close(ld->which[idx]); ld->which[idx] = -1;
+    CLOSE(wakeup_fds, 0); CLOSE(wakeup_fds, 1);
+    CLOSE(signal_fds, 0); CLOSE(signal_fds, 1);
+#undef CLOSE
+    if (ld->signal_read_fd) {
+        signal_write_fd = -1;
+        signal(SIGINT, SIG_DFL);
+        signal(SIGTERM, SIG_DFL);
+        signal(SIGCHLD, SIG_DFL);
+    }
+    ld->signal_read_fd = -1; ld->wakeup_read_fd = -1;
+}
+
+
+void
+wakeup_loop(LoopData *ld, bool in_signal_handler) {
+    while(true) {
+        ssize_t ret = write(ld->wakeup_fds[1], "w", 1);
+        if (ret < 0) {
+            if (errno == EINTR) continue;
+            if (!in_signal_handler) log_error("Failed to write to loop wakeup fd with error: %s", strerror(errno));
+        }
+        break;
+    }
+}
+
+
+
+bool
+install_signal_handlers(LoopData *ld) {
+    if (!self_pipe(ld->signal_fds, true)) return false;
+    signal_write_fd = ld->signal_fds[1];
+    struct sigaction act = {.sa_handler=handle_signal};
+#define SA(which) { if (sigaction(which, &act, NULL) != 0) return false; if (siginterrupt(which, false) != 0) return false; }
+    SA(SIGINT); SA(SIGTERM); SA(SIGCHLD);
+#undef SA
+    ld->signal_read_fd = ld->signal_fds[0];
+    return true;
+}
+
+static inline void
+read_signals_from_pipe_fd(int fd, handle_signal_func callback, void *data) {
+    static char buf[256];
+    while(true) {
+        ssize_t len = read(fd, buf, sizeof(buf));
+        if (len < 0) {
+            if (errno == EINTR) continue;
+            if (errno != EIO && errno != EAGAIN) log_error("Call to read() from read_signals_from_pipe_fd() failed with error: %s", strerror(errno));
+            break;
+        }
+        for (ssize_t i = 0; i < len; i++) callback(buf[i], data);
+        if (len == 0) break;
+    }
+}
+
+void
+read_signals(int fd, handle_signal_func callback, void *data) {
+    read_signals_from_pipe_fd(fd, callback, data);
+}